Articular Cartilage- and Synoviocyte-Binding Poly(ethylene glycol) Nanocomposite Microgels as Intra-Articular Drug Delivery Vehicles for the Treatment of Osteoarthritis

Advances in locally administered nucleic acid therapeutics

Nucleic acid drugs represent the latest generation of precision therapeutics, holding significant promise for the treatment of a wide range of intractable diseases. Delivery technology is crucial for the clinical application of nucleic acid drugs. However, extrahepatic delivery of nucleic acid drugs remains a significant challenge. Systemic administration often fails to achieve sufficient drug enrichment in target tissues. Localized administration has emerged as the predominant approach to facilitate extrahepatic delivery. While localized administration can significantly enhance drug accumulation at the injection sites, nucleic acid drugs still face biological barriers in reaching the target lesions. This review focuses on non-viral nucleic acid drug delivery techniques utilized in local administration for the treatment of extrahepatic diseases. First, the classification of nucleic acid drugs is described. Second, the current major non-viral delivery technologies for nucleic acid drugs are discussed. Third, the bio-barriers, administration approaches, and recent research advances in the local delivery of nucleic acid drugs for treating lung, brain, eye, skin, joint, and heart-related diseases are highlighted. Finally, the challenges associated with the localized therapeutic application of nucleic acid drugs are addressed.

Multiscale characterization of ultrasmall fluorescent core-shell silica nanoparticles in cartilage and synovial joints reveals rapid cartilage penetration and sustained joint residence

Development of non-surgical disease-modifying interventions for knee osteoarthritis (OA) remains a persistent challenge despite decades of efforts. Therapeutic transport to cartilage in synovial joints is hindered by the dense, negatively charged cartilage matrix, and further challenged by rapid synovial fluid clearance within hours to days. In this study, we investigated ultrasmall (dh ∼ 6 nm) fluorescent core-shell silica nanoparticles (Cornell Prime Dots, or C' Dots), which have received FDA-investigational new drug approval for multiple human clinical trials in oncology, as cartilage-penetrating delivery vehicles for applications in knee OA. Across multiple length and time scales, we examined the relationship between C' Dot tissue and cellular transport kinetics and whole joint clearance. In vitro, C' Dots penetrated cartilage explants within 30 min (D ∼ 2 µm2/s). C' Dots were internalized by chondrocytes within 24 h and were retained in vesicular structures for up to 5 days. In vivo, C' Dot clearance following intra-articular knee injection was well described by two distinct time constants (τ1 ∼ 18 hours, τ2 ∼ 3 weeks), consistent with mechanisms of synovial- and tissue-mediated clearance. C' Dot clearance rates were not affected by surgically-induced cruciate ligament transection. Notably, C' Dots remained in the knee longer than 3 months after a single injection and were localized to cartilage, meniscus, ligaments, and synovium. Collectively, these results illustrate the potential of C' Dots for long-term delivery of conjugated therapeutics in the knee. STATEMENT OF SIGNIFICANCE: This research explores a cartilage-penetrating platform nanotechnology for applications in drug delivery for arthritis. The properties inherent to this particle system enabled rapid tissue penetration, chondrocyte internalization and retention, and persistence in rat knees for longer than 3 months after a single injection. The study demonstrates that ultrasmall nanoparticle delivery platforms can use tissue localization to partially avoid clearance by the synovium, while simultaneously enabling chondrocyte targeting. When paired with a therapeutic, C' Dots may be a versatile platform in early-stage OA and PTOA to protect cartilage from further degeneration. These findings inform future design and engineering of biocompatible drug delivery vehicles for other applications where access to dense tissues is needed.

Nanomaterial-Based Drug Delivery Systems Targeting Functional Cells for Osteoarthritis Treatment: Mechanisms, Challenges and Future Prospects

Osteoarthritis (OA) represents a chronic joint disease characterized by articular cartilage degeneration, synovial inflammation, and subchondral bone erosions. Functional cells in OA mainly include macrophages, synoviocytes, chondrocytes, and mesenchymal stem cells. These cells can secrete cytokines and non-coding RNAs and exosomes and interact with each other to coregulate the progression of OA. Some nanomaterial-based drug delivery systems (DDSs) surface ligands can alleviate OA by targeting receptors on the surface of functional cells. Meanwhile, other nanomaterial-based DDSs, whose surfaces are masked by the cell membranes or extracellular vesicles of these functional cells, treat OA by targeting and attacking the diseased site. When ligand-modified nanomaterials target specific functional cells to treat OA, the functional cells are attacked. Functional cells become attackers, similar to arrows, when their cell membranes or extracellular vesicles are modified into nanomaterials to deliver drugs for OA treatment. An increasing number of studies have been conducted on nanomaterial-based DDS-targeted functional cells for the treatment of OA, but none has summarized the corresponding research progress and mechanism of action. In this review, the related references on the treatment of osteoarthritis with nanomaterial-based DDSs targeting functional cells have been included, and how a variety of functional cells can be engineered into nanomaterial-based DDSs serving as targets or arrows to treat OA has been summarised for the first time, providing a new idea and method for the targeted treatment of OA.

Research progress on biodegradable polymer-based drug delivery systems for the treatment of knee osteoarthritis

Knee osteoarthritis (KOA) is a disease that involves multiple anatomical and physiological changes in the knee tissues, including cartilage degeneration, bone remodelling and formation of bony encumbrances, which leads to clinical manifestations including pain, stiffness, swelling and limitation of knee function. Knee osteoarthritis is a chronic joint disease characterised by degenerative cartilage lesions and secondary osteophytes in the knee joint. The symptoms of knee osteoarthritis tend to progress slowly, and at this stage, the number of patients with KOA is increasing. However, due to the adverse effects and poor therapeutic outcomes following surgical treatment, intervention therapy through the utilisation of biodegradable polymeric materials is required. Currently, clinical aspects are mainly used to treat cartilage degeneration in patients with osteoarthritis of the knee by using different kinds of biodegradable biopolymer materials with excellent physical properties, histocompatibility and other properties, combined with a drug delivery system, which can reduce the level of inflammation and stiffness in the focal area, and maximise the restoration of the patient's knee joint joint mobility and athletic ability. Based on the properties of the polymeric material drug delivery system, the polymeric material has a variable drug loading capacity that encapsulates hydrophobic/hydrophilic drugs and controls the release kinetics by regulating the composition and charge. This paper reviews the research progress of Poly (ε-caprolactone) (PCL), Poly(lactic acid) (PLA), Poly (lactic glycolic acid) (PLGA), Poly(ethylene glycol) (PEG) synthetic polymers and collagen, chondroitin sulfate, other natural polymers based drug delivery systems for the treatment of knee osteoarthritis, and explains that different biodegradable polymeric materials have been widely used for the treatment of knee osteoarthritis. However, there are still issues of degradability, toxicity, compatibility, and durability and safety of the drug delivery system of degradable materials that need to be addressed in further clinical trials. As biodegradable biomedical materials continue to be explored, eventually idealized polymeric materials will stand out in the treatment of KOA.

Innovative Biotherapies and Nanotechnology in Osteoarthritis: Advancements in Inflammation Control and Cartilage Regeneration

Osteoarthritis (OA) is among the most prevalent degenerative joint disorders worldwide, particularly affecting the aging population and imposing significant disability and economic burdens. The disease is characterized by progressive degradation of articular cartilage and chronic inflammation, with no effective long-term treatments currently available to address the underlying causes of its progression. Conventional therapies primarily manage symptoms such as pain and inflammation but fail to repair damaged tissues. Emerging biotherapies and regenerative medicine approaches offer promising alternatives by addressing cartilage repair and inflammation control at the molecular level. This review explores the recent advancements in biotherapeutic strategies, including mesenchymal stem cell (MSC) therapy, growth factors, and tissue engineering, which hold the potential for promoting cartilage regeneration and modulating the inflammatory microenvironment. Additionally, the integration of nanotechnology has opened new avenues for targeted drug delivery systems and the development of innovative nanomaterials that can further enhance the efficacy of biotherapies by precisely targeting inflammation and cartilage damage. This article concludes by discussing the current clinical applications, the ongoing clinical trials, and the future research directions necessary to confirm the safety and efficacy of these advanced therapies for OA management. With these advancements, biotherapies combined with nanotechnology may revolutionize the future of OA treatment by offering precise and effective solutions for long-term disease management and improved patient outcomes.

Advances in viscosupplementation and tribosupplementation for early-stage osteoarthritis therapy

Joint kinematic instability, arising from congenital or acquired musculoskeletal pathoanatomy or from imbalances in anabolism and catabolism induced by pathophysiological factors, leads to deterioration of the composition, structure and function of cartilage and, ultimately, progression to osteoarthritis (OA). Alongside articular cartilage degeneration, synovial fluid lubricity decreases in OA owing to a reduction in the concentration and molecular weight of hyaluronic acid and surface-active mucinous glycoproteins that form a lubricating film over the articulating joint surfaces. Minimizing friction between articulating joint surfaces by lubrication is fundamental for decreasing hyaline cartilage wear and for maintaining the function of synovial joints. Augmentation with highly viscous supplements (that is, viscosupplementation) offers one approach to re-establishing the rheological and tribological properties of synovial fluid in OA. However, this approach has varied clinical outcomes owing to limited intra-articular residence time and ineffective mechanisms of chondroprotection. This Review discusses normal hyaline cartilage function and lubrication and examines the advantages and disadvantages of various strategies for restoring normal joint lubrication. These strategies include contemporary viscosupplements that contain antioxidants, anti-inflammatory drugs or platelet-rich plasma and new synthetic synovial fluid additives and cartilage matrix enhancers. Advanced biomimetic tribosupplements offer promise for mitigating cartilage wear, restoring joint function and, ultimately, improving patient care.

Branched poly-l-lysine for cartilage penetrating carriers

Joint diseases, such as osteoarthritis, often require delivery of drugs to chondrocytes residing within the cartilage. However, intra-articular delivery of drugs to cartilage remains a challenge due to their rapid clearance within the joint. This problem is further exacerbated by the dense and negatively charged cartilage extracellular matrix (ECM). Cationic nanocarriers that form reversible electrostatic interactions with the anionic ECM can be an effective approach to overcome the electrostatic barrier presented by cartilage tissue. For an effective therapeutic outcome, the nanocarriers need to penetrate, accumulate, and be retained within the cartilage tissue. Nanocarriers that adhere quickly to cartilage tissue after intra-articular administration, transport through cartilage, and remain within its full thickness are crucial to the therapeutic outcome. To this end, we used ring-opening polymerization to synthesize branched poly(l-lysine) (BPL) cationic nanocarriers with varying numbers of poly(lysine) branches, surface charge, and functional groups, while maintaining similar hydrodynamic diameters. Our results show that the multivalent BPL molecules, including those that are highly branched (i.e., generation two), can readily adhere and transport through the full thickness of cartilage, healthy and degenerated, with prolonged intra-cartilage retention. Intra-articular injection of the BPL molecules in mouse knee joint explants and rat knee joints showed their localization and retention. In summary, this study describes an approach to design nanocarriers with varying charge and abundant functional groups while maintaining similar hydrodynamic diameters to aid the delivery of macromolecules to negatively charged tissues.

A Functional Hydrogel Bead-Based High-Throughput Screening System for Mammalian Cells with Enhanced Secretion of Therapeutic Antibodies

Droplet-based high-throughput screening systems are an emerging technology that provides a quick test to screen millions of cells with distinctive characteristics. Biopharmaceuticals, specifically therapeutic proteins, are produced by culturing cells that secrete heterologous recombinant proteins with different populations and expression levels; therefore, a technology to discriminate cells that produce more target proteins is needed. Here, we present a droplet-based microfluidic strategy for encapsulating, screening, and selecting target cells with redox-responsive hydrogel beads (HBs). As a proof-of-concept study, we demonstrate the enrichment of hybridoma cells with enhanced capability of antibody secretion using horseradish peroxidase (HRP)-catalyzed hydrogelation of tetra-thiolate poly(ethylene glycol); hybridoma cells were encapsulated in disulfide-bonded HBs. Recombinant protein G or protein M with a C-terminal cysteine residue was installed in the HBs via disulfide bonding to capture antibodies secreted from the cells. HBs were fluorescently stained by adding the protein L-HRP conjugate using a tyramide signal amplification system. HBs were then separated by fluorescence-activated droplet sorting and degraded by reducing the disulfide bonds to recover the target cells. Finally, we succeeded in the selection of hybridoma cells with enhanced antibody secretion, indicating the potential of this system in the therapeutic protein production.

Progress in microsphere-based scaffolds in bone/cartilage tissue engineering

Bone/cartilage repair and regeneration have been popular and difficult issues in medical research. Tissue engineering is rapidly evolving to provide new solutions to this problem, and the key point is to design the appropriate scaffold biomaterial. In recent years, microsphere-based scaffolds have been considered suitable scaffold materials for bone/cartilage injury repair because microporous structures can form more internal space for better cell proliferation and other cellular activities, and these composite scaffolds can provide physical/chemical signals for neotissue formation with higher efficiency. This paper reviews the research progress of microsphere-based scaffolds in bone/chondral tissue engineering, briefly introduces types of microspheres made from polymer, inorganic and composite materials, discusses the preparation methods of microspheres and the exploration of suitable microsphere pore size in bone and cartilage tissue engineering, and finally details the application of microsphere-based scaffolds in biomimetic scaffolds, cell proliferation and drug delivery systems.

The potential role of synovial cells in the progression and treatment of osteoarthritis

Osteoarthritis (OA), the commonest arthritis, is characterized by the progressive destruction of cartilage, leading to disability. The Current early clinical treatment strategy for OA often centers on anti-inflammatory or analgesia medication, weight loss, improved muscular function and articular cartilage repair. Although these treatments can relieve symptoms, OA tends to be progressive, and most patients require arthroplasty at the terminal stages of OA. Recent studies have shown a close correlation between joint pain, inflammation, cartilage destruction and synovial cells. Consequently, understanding the potential mechanisms associated with the action of synovial cells in OA could be beneficial for the clinical management of OA. Therefore, this review comprehensively describes the biological functions of synovial cells, the synovium, together with the pathological changes of synovial cells in OA, and the interaction between the cartilage and synovium, which is lacking in the present literature. Additionally, therapeutic approaches based on synovial cells for OA treatment are further discussed from a clinical perspective, highlighting a new direction in the treatment of OA.

Arthritic Microenvironment-Dictated Fate Decisions for Stem Cells in Cartilage Repair

The microenvironment and stem cell fate guidance of post-traumatic articular cartilage regeneration is primarily the focus of cartilage tissue engineering. In articular cartilage, stem cells are characterized by overlapping lineages and uneven effectiveness. Within the first 12 weeks after trauma, the articular inflammatory microenvironment (AIME) plays a decisive role in determining the fate of stem cells and cartilage. The development of fibrocartilage and osteophyte hyperplasia is an adverse outcome of chronic inflammation, which results from an imbalance in the AIME during the cartilage tissue repair process. In this review, the sources for the different types of stem cells and their fate are summarized. The main pathophysiological events that occur within the AIME as well as their protagonists are also discussed. Additionally, regulatory strategies that may guide the fate of stem cells within the AIME are proposed. Finally, strategies that provide insight into AIME pathophysiology are discussed and the design of new materials that match the post-traumatic progress of AIME pathophysiology in a spatial and temporal manner is guided. Thus, by regulating an appropriately modified inflammatory microenvironment, efficient stem cell-mediated tissue repair may be achieved.

Recent Advances in Small Molecule Inhibitors for the Treatment of Osteoarthritis

Osteoarthritis refers to a degenerative disease with joint pain as the main symptom, and it is caused by various factors, including fibrosis, chapping, ulcers, and loss of articular cartilage. Traditional treatments can only delay the progression of osteoarthritis, and patients may need joint replacement eventually. As a class of organic compound molecules weighing less than 1000 daltons, small molecule inhibitors can target proteins as the main components of most drugs clinically. Small molecule inhibitors for osteoarthritis are under constant research. In this regard, by reviewing relevant manuscripts, small molecule inhibitors targeting MMPs, ADAMTS, IL-1, TNF, WNT, NF-κB, and other proteins were reviewed. We summarized these small molecule inhibitors with different targets and discussed disease-modifying osteoarthritis drugs based on them. These small molecule inhibitors have good inhibitory effects on osteoarthritis, and this review will provide a reference for the treatment of osteoarthritis.

Nanodevices for deep cartilage penetration

Osteoarthritis (OA) is a degenerative joint disease and is the main cause of chronic pain and functional disability in adults. Articular cartilage is a hydrated soft tissue that is composed of normally quiescent chondrocytes at a low density, a dense network of collagen fibrils with a pore size of 60-200 nm, and aggrecan proteoglycans with high-density negative charge. Although certain drugs, nucleic acids, and proteins have the potential to slow the progression of OA and restore the joints, these treatments have not been clinically applied owing to the lack of an effective delivery system capable of breaking through the cartilage barrier. Recently, the development of nanotechnology for delivery systems renders new ideas and treatment methods viable in overcoming the limited penetration. In this review, we focus on current research on such applications of nanotechnology, including exosomes, protein-based cationic nanocarriers, cationic liposomes/solid lipid nanoparticles, amino acid-based nanocarriers, polyamide derivatives-based nanocarriers, manganese dioxide, and carbon nanotubes. Exosomes are the smallest known nanoscale extracellular vesicles, and they can quickly deliver nucleic acids or proteins to the required depth. Through electrostatic interactions, nanocarriers with appropriate balance in cationic property and particle size have a strong ability to penetrate cartilage. Although substantial preclinical evidence has been obtained, further optimization is necessary for clinical transformation. STATEMENT OF SIGNIFICANCE: The dense cartilage matrix with high-negative charge was associated with reduced therapeutic effect in osteoarthritis patients with deep pathological changes. However, a systematic review in nanodevices for deep cartilage penetration is still lacking. Current approaches to assure penetration of nanosystems into the depth of cartilage were reviewed, including nanoscale extracellular vesicles from different cell lines and nanocarriers with appropriate balance in cationic property and size particle. Moreover, nanodevices entering clinical trials and further optimization were also discussed, providing important guiding significance to future research.

Applications and prospects of intra-articular drug delivery system in arthritis therapeutics

Arthritis is a kind of chronic disease that affects joints and muscles with the symptoms of joint pain, inflammation and limited movement of joints. Among various clinical therapies, drug therapy has been extensively applied because of its accessibility, safety and effectiveness. In recent years, the intra-articular injection has dramatic therapeutic effects in treating arthritis with high patient compliance and low side effects. In this review, we will introduce pathology of arthritis, along with the accessible treatment and diagnosis methods, then we will summarize major advances of current hopeful intra-articular delivery systems such as microspheres, hydrogels, nanoparticles and liposomes. At last, some safety assessments in the preclinical work and the main challenges for the further development of intra-articular treatment were also discussed.

Microgel-Assisted Delivery of Adenosine to Accelerate Fracture Healing

Extracellular adenosine plays a key role in promoting bone tissue formation. Local delivery of adenosine could be an effective therapeutic strategy to harness the beneficial effect of extracellular adenosine on bone tissue formation following injury. Herein, we describe the development of an injectable in situ curing scaffold containing microgel-based adenosine delivery units. The two-component scaffold includes adenosine-loaded microgels and functionalized hyaluronic acid (HA) molecules. The microgels were generated upon copolymerization of 3-acrylamidophenylboronic acid (3-APBA)- and 2-aminoethylmethacrylamide (2-AEMA)-conjugated HA (HA-AEMA) in an emulsion suspension. The PBA functional groups were used to load the adenosine molecules. Mixing of the microgels with the HA polymers containing clickable groups, dibenzocyclooctyne (DBCO) and azide (HA-DBCO and HA-Azide), resulted in a 3D scaffold embedded with adenosine delivery units. Application of the in situ curing scaffolds containing adenosine-loaded microgels following tibial fracture injury showed improved bone tissue healing in a mouse model as demonstrated by the reduced callus size, higher bone volume, and increased tissue mineral density compared to those treated with the scaffold without adenosine. Overall, our results suggest that local delivery of adenosine could potentially be an effective strategy to promote bone tissue repair.

Dual role of injectable curcumin-loaded microgels for efficient repair of osteoarthritic cartilage injury

Curcumin has been widely used for the treatment of age-associated diseases, and showed chondroprotective potential for post-traumatic osteoarthritis (OA). However, due to the irregular-shaped and large-sized defects on joint cartilage in degenerated OA, the in vivo delivery and therapeutic effect of curcumin for effective repair remain challenging. In this study, we first present a PEG-GelMA [Poly(Ethylene Glycol) Dimethacrylate-Gelatin Methacrylate, PGMs] hydrogel microgel-based curcumin delivery system for both improved anti-inflammatory and pro-regenerative effects in treatment for cartilage defects. The curcumin-loaded PGMs were produced by a microfluidic system based on light-induced gelation of gelatin methacrylate (GelMA). This PGMs embedding curcumin at a relative low dosage were demonstrated to promote the proliferation and chondrogenic differentiation of mesenchymal stem cells in vitro. More importantly, the PGMs were shown to attenuate the inflammatory response of chondrocytes under IL-1β stimulation. Lastly, the in vivo application of the injectable PGMs significantly promoted the repair of large-sized cartilage injury. These results confirmed that curcumin-loaded PGMs can not only enhance the chondroprotective efficacy under inflammatory conditions but also induce efficient cartilage regeneration. This study provides an advanced strategy with anti-inflammatory and pro-regenerative dual-role therapeutic for treatment of extensive cartilage injuries.

Benefits of Applying Nanotechnologies to Hydrogels in Efficacy Tests in Osteoarthritis Models-A Systematic Review of Preclinical Studies

Osteoarthritis (OA) is a severe musculoskeletal disease with an increasing incidence in the worldwide population. Recent research has focused on the development of innovative strategies to prevent articular cartilage damage and slow down OA progression, and nanotechnologies applied to hydrogels have gained particular interest. The aim of this systematic review is to investigate the state of the art on preclinical in vitro and in vivo efficacy studies applying nanotechnologies to hydrogels in OA models to elucidate the benefits of their applications. Three databases were consulted for eligible papers. The inclusion criteria were in vitro and in vivo preclinical studies, using OA cells or OA animal models, and testing hydrogels and nanoparticles (NPs) over the last ten years. Data extraction and quality assessment were performed. Eleven papers were included. In vitro studies evidenced that NP-gels do not impact on cell viability and do not cause inflammation in OA cell phenotypes. In vivo research on rodents showed that these treatments could increase drug retention in joints, reducing inflammation and preventing articular cartilage damage. Nanotechnologies in preclinical efficacy tests are still new and require extensive studies and technical hits to determine the efficacy, safety, fate, and localization of NPs for translation into an effective therapy for OA patients.

Relative Efficacy and Safety of Anti-Inflammatory Biologic Agents for Osteoarthritis: A Conventional and Network Meta-Analysis

Previous studies have consistently revealed that both local and systemic inflammations are the key to the onset and progression of osteoarthritis (OA). Thus, anti-inflammatory biologic agents could potentially attenuate the progression of OA. We conducted this meta-analysis to examine the efficacy and safety of ant-inflammatory biologic agents among OA patients.

METHODS

Five databases were searched for randomized controlled trials (RCTs) comparing biologics with placebo or each other in OA patients. Data of pain, physical function, stiffness, and adverse events (AEs) were extracted for a conventional and a Bayesian network meta-analysis.

RESULTS

15 studies with data for 1566 patients were analyzed. In the conventional meta-analysis, etanercept (SMD -0.47; 95% CI -0.89, -0.05) and infliximab (SMD -2.04; CI -2.56, -1.52) were superior to placebo for knee pain. In the network meta-analysis, infliximab was superior to all the other biologic agents in improving pain (vs. hyaluronic acid (SMD -22.95; CI -34.21, -10.43), vs. adalimumab (SMD -21.71; CI -32.65, -11.00), vs. anakinra (SMD -24.63; CI -38.79, -10.05), vs. canakinumab (SMD -32.83; CI -44.45, -20.68), vs. etanercept (SMD -18.40; CI -29.93, -5.73), vs. lutikizumab (SMD -25.11; CI -36.47, -14.78), vs. naproxen (SMD -30.16; CI -41.78, -17.38), vs. tocilizumab (SMD -24.02; CI -35.63, -11.86) and vs. placebo (SMD -25.88; CI -34.87, -16.60)). No significant differences were observed between biologics and placebo regarding physical function, stiffness, and risk of AEs.

CONCLUSIONS

The findings suggest that infliximab may relieve pain more than other biological agents in OA patients. No significant differences were observed between biologics and placebo regarding physical function, stiffness, and risk of AEs. The results must be interpreted cautiously; therefore, further randomized controlled trials are warranted.

Implantable biosensors for musculoskeletal health

PURPOSE

A healthy musculoskeletal system requires complex functional integration of bone, muscle, cartilage, and connective tissues responsible for bodily support, motion, and the protection of vital organs. Conditions or injuries to musculoskeeltal tissues can devastate an individual's quality of life. Some conditions that are particularly disabling include severe bone and muscle injuries to the extremities and amputations resulting from unmanageable musculoskeletal conditions or injuries. Monitoring and managing musculoskeletal health is intricate because of the complex mechanobiology of these interconnected tissues.

METHODS

For this article, we reviewed literature on implantable biosensors related to clinical data of the musculoskeletal system, therapeutics for complex bone injuries, and osseointegrated prosthetics as example applications.

RESULTS

As a result, a brief summary of biosensors technologies is provided along with review of noteworthy biosensors and future developments needed to fully realize the translational benefit of biosensors for musculoskeletal health.

CONCLUSIONS

Novel implantable biosensors capable of tracking biophysical parameters in vivo are highly relevant to musculoskeletal health because of their ability to collect clinical data relevant to medical decisions, complex trauma treatment, and the performance of osseointegrated prostheses.

Knee Osteoarthritis Therapy: Recent Advances in Intra-Articular Drug Delivery Systems

Drug delivery for osteoarthritis (OA) treatment is a continuous challenge because of their poor bioavailability and rapid clearance in joints. Intra-articular (IA) drug delivery is a common strategy and its therapeutic effects depend mainly on the efficacy of the drug-delivery system used for OA therapy. Different types of IA drug-delivery systems, such as microspheres, nanoparticles, and hydrogels, have been rapidly developed over the past decade to improve their therapeutic effects. With the continuous advancement in OA mechanism research, new drugs targeting specific cell/signaling pathways in OA are rapidly evolving and effective drug delivery is critical for treating OA. In this review, recent advances in various IA drug-delivery systems for OA treatment, OA targeted strategies, and related signaling pathways in OA treatment are summarized and analyzed based on current publications.

Management of osteoarthritis: From drug molecules to nano/micromedicines

With the change in lifestyle and aging of the population, osteoarthritis (OA) is emerging as a major medical burden globally. OA is a chronic inflammatory and degenerative disease initially manifesting with joint pain and eventually leading to permanent disability. To date, there are no drugs available for the definitive treatment of osteoarthritis and most therapies have been palliative in nature by alleviating symptoms rather than curing the disease. This coupled with the vague understanding of the early symptoms and methods of diagnosis so that the disease continues as a global problem and calls for concerted research efforts. A cascade of events regulates the onset and progression of osteoarthritis starting with the production of proinflammatory cytokines, including interleukin (IL)‐1β, IL‐6, tumor necrosis factor (TNF)‐α; catabolic enzymes, such as matrix metalloproteinases (MMPs)‐1, ‐3, and ‐13, culminating into cartilage breakdown, loss of lubrication, pain, and inability to load the joint. Although intra‐articular injections of small and macromolecules are often prescribed to alleviate symptoms, low residence times within the synovial cavity severely impair their efficacy. This review will briefly describe the factors dictating the onset and progression of the disease, present the current clinically approved methods for its treatment and diagnosis, and finally elaborate on the main challenges and opportunities for the application of nano/micromedicines in the treatment of osteoarthritis. Thus, future treatment regimens will benefit from simultaneous consideration of the mechanobiological, the inflammatory, and tissue degradation aspects of the disease.

This article is categorized under:

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement

Emerging microfluidics-enabled platforms for osteoarthritis management: from benchtop to bedside

Osteoarthritis (OA) is a prevalent debilitating age-related joint degenerative disease. It is a leading cause of pain and functional disability in older adults. Unfortunately, there is no cure for OA once the damage is established. Therefore, it promotes an urgent need for early detection and intervention of OA. Theranostics, combining therapy and diagnosis, emerges as a promising approach for OA management. However, OA theranostics is still in its infancy. Three fundamental needs have to be firstly fulfilled: i) a reliable OA model for disease pathogenesis investigation and drug screening, ii) an effective and precise diagnostic platform, and iii) an advanced fabrication approach for drug delivery and therapy. Meanwhile, microfluidics emerges as a versatile technology to address each of the needs and eventually boost the development of OA theranostics. Therefore, this review focuses on the applications of microfluidics, from benchtop to bedside, for OA modelling and drug screening, early diagnosis, and clinical therapy. We first introduce the basic pathophysiology of OA and point out the major unfilled research gaps in current OA management including lack of disease modelling and drug screening platforms, early diagnostic modalities and disease-modifying drugs and delivery approaches. Accordingly, we then summarize the state-of-the-art microfluidics technology for OA management from in vitro modelling and diagnosis to therapy. Given the existing promising results, we further discuss the future development of microfluidic platforms towards clinical translation at the crossroad of engineering and biomedicine.

Intra-Articular Drug Delivery for Osteoarthritis Treatment

Osteoarthritis (OA) is the most prevalent degenerative joint disease affecting millions of people worldwide. Currently, clinical nonsurgical treatments of OA are only limited to pain relief, anti-inflammation, and viscosupplementation. Developing disease-modifying OA drugs (DMOADs) is highly demanded for the efficient treatment of OA. As OA is a local disease, intra-articular (IA) injection directly delivers drugs to synovial joints, resulting in high-concentration drugs in the joint and reduced side effects, accompanied with traditional oral or topical administrations. However, the injected drugs are rapidly cleaved. By properly designing the drug delivery systems, prolonged retention time and targeting could be obtained. In this review, we summarize the drugs investigated for OA treatment and recent advances in the IA drug delivery systems, including micro- and nano-particles, liposomes, and hydrogels, hoping to provide some information for designing the IA injected formulations.

Cell-laden injectable microgels: Current status and future prospects for cartilage regeneration

Injectable hydrogels have been employed extensively as versatile materials for cartilage regeneration due to their excellent biocompatibility, tunable structure, and ability to accommodate bioactive factors, as well as their ability to be locally delivered via minimally invasive injection to fill irregular defects. More recently, in vitro and in vivo studies have revealed that processing these materials to produce cell-laden microgels can enhance cell-cell and cell-matrix interactions and boost nutrient and metabolite exchange. Moreover, these studies have demonstrated gene expression profiles and matrix regeneration that are superior compared to conventional injectable bulk hydrogels. As cell-laden microgels and their application in cartilage repair are moving closer to clinical translation, this review aims to present an overview of the recent developments in this field. Here we focus on the currently used biomaterials and crosslinking strategies, the innovative fabrication techniques being used for the production of microgels, the cell sources used, the signals used for induction of chondrogenic differentiation and the resultant biological responses, and the ability to create three-dimensional, functional cartilage tissues. In addition, this review also covers the current clinical approaches for repairing cartilage as well as specific challenges faced when attempting the regeneration of damaged cartilage tissue. New findings related to the macroporous nature of the structures formed by the assembled microgel building blocks and the novel use of microgels in 3D printing for cartilage tissue engineering are also highlighted. Finally, we outline the challenges and future opportunities for employing cell-laden microgels in clinical applications.

Thermo-responsive injectable naringin-loaded hydrogel polymerised sodium alginate/bioglass delivery for articular cartilage

In the human body, joint cartilage is of great importance. It has long been a big therapeutic problem to fix joint cartilage lesions as it appears due to different conditions. Recent stories have shown that the cartilage replacement process must delay the extracellular (ECM) cartilage deterioration and modulate the host's inflammation response. For the reconstruction of the articular cartilage, drug-loaded injectable hydrogels were developed. This hydrogel could retain the chondrocyte phenotype, but the host's inflammatory reaction could also be controlled. The bioglass (BG)/sodium alginate (SA) injectable hydrogels was combined with agarose (AG)/Naringin hydrogel in injectable thermal response for articular cartilage regeneration with a non-chargeable hydrogel that contains both Naringin and BG (Naringin–BG hydrogels). The Naringin–BG hydrogel has an adequate swelling ratio that encourages the fusion of tissue formed with host tissue and enables the gradual release of Naringin bioavailabilities enhanced in situ. The Naringin–BG hydrogel can upgrade the typical chondrocyte phenotype by upregulating aggrecan, SRY-box 9, and collagen type II alpha one chain. It may also stimulate the polarization of M2 macrophage, lower inflammations, and prevent ECM degradations through the decrease of the expressions of the indictable metalloproteinase-13 matrix, nitric oxide synthase, and metalloproteinase-1 matrix. The formed tissues were identical to normal tissues and firmly incorporated with the surrounding tissue after administering the Naringin–BG hydrogels into the rat model articular cartilage defects. Then the injectable Naringin–BG hydrogel increases the bioavailable content of Naringin and retains the chondrocyte phenotype.

Enhanced In Vitro and In Vivo Efficacy of Alginate/Silk Protein/Hyaluronic Acid with Polypeptide Microsphere Delivery for Tissue Regeneration of Articular Cartilage

Alginate/Silk fibroin/hyaluronic acid (ALG/SF/HA) nanocomposites were synthesised using blending, inter-linking, and lyophilization methods. We investigated the physicochemical properties of the resulting nanocomposites, including their water retention, weight loss, porosity and cytocompatibility. The optimum ratios of the ALG/SF/HA scaffolding were 3:6.5:0.5. Nanocomposites with optimum ratios were then prepared by integrating pilose antler polypeptides (PAPS) to poly(lactic-co-glycolic acid) (PLGA) microspheres, and the performance was investigated. PAPS-ALG/SF/HA nanocomposites exhibited desirable adhesions and proliferations. Rabbit cartilage deficiencies was developed by the animal model. The cartilage repair effects deficiencies were detected and analyzed between PAPS-SF/ALG/ALG/SF/HA, and control activity classes. The deficiencies were virtually fully remedied after 13 weeks in the presence of PAPS-ALG/SF/HA class, suggesting that the PAPS-ALG/SF/HA nanocomposites had a positive effects on joint cartilage repair.

Biomaterials for protein delivery for complex tissue healing responses

Tissue repair requires a complex cascade of events mediated by a variety of cells, proteins, and matrix molecules; however, the healing cascade can be easily disrupted by numerous factors, resulting in impaired tissue regeneration. Recent advances in biomaterials for tissue regeneration have increased the ability to tailor the delivery of proteins and other biomolecules to injury sites to restore normal healing cascades and stimulate robust tissue repair. In this review, we discuss the evolution of the field toward creating biomaterials that precisely control protein delivery to stimulate tissue regeneration, with a focus on addressing complex and dynamic injury environments. We highlight biomaterials that leverage different mechanisms to deliver and present proteins involved in healing cascades, tissue targeting and mimicking strategies, materials that can be triggered by environmental cues, and integrated strategies that combine multiple biomaterial properties to improve protein delivery. Improvements in biomaterial design to address complex injury environments will expand our understanding of both normal and aberrant tissue repair processes and ultimately provide a better standard of patient care.

Recent advances in targeted drug delivery for treatment of osteoarthritis

PURPOSE OF REVIEW

Osteoarthritis is associated with severe joint pain, inflammation, and cartilage degeneration. Drugs injected directly into intra-articular joint space clear out rapidly providing only short-term benefit. Their transport into cartilage to reach cellular targets is hindered by the tissue's dense, negatively charged extracellular matrix. This has limited, despite strong preclinical data, the clinical translation of osteoarthritis drugs. Recent work has focused on developing intra-joint and intra-cartilage targeting drug delivery systems (DDS) to enable long-term therapeutic response, which is presented here.

RECENT FINDINGS

Synovial joint targeting hybrid systems utilizing combinations of hydrogels, liposomes, and particle-based carriers are in consideration for pain-inflammation relief. Cartilage penetrating DDS target intra-cartilage constituents like aggrecans, collagen II, and chondrocytes such that drugs can reach their cellular and intra-cellular targets, which can enable clinical translation of disease-modifying osteoarthritis drugs including gene therapy.

SUMMARY

Recent years have witnessed significant increase in both fundamental and clinical studies evaluating DDS for osteoarthritis. Steroid encapsulating polymeric microparticles for longer lasting pain relief were recently approved for clinical use. Electrically charged biomaterials for intra-cartilage targeting have shown promising disease-modifying response in preclinical models. Clinical trials evaluating safety of viral vectors are ongoing whose success can pave the way for gene therapy as osteoarthritis treatment.